What do you do with an organisation that has correctly predicted the world's financial crashes; that has led debates over how to make poor countries richer; and that provides a voice to developing nations? Well, if you're David Cameron or Barack Obama, you try to silence it. Its warnings over the danger of letting markets run amok have made the United Nations Conference on Trade and Development, or Unctad, a persistent irritant to America and Britain. Now, ahead of its conference this month, the agency is under threat from rich countries who want it to keep out of the big issues about how the world's economy is run, and to stick to touchy-feely stuff instead. This would be a huge mistake. Compared to those behemoths, the IMF and World Bank, the smaller Geneva-based agency is on the right side of the argument. Those who want a fairer, more sustainable world economy should want Unctad not to pipe down, but to speak up.